Cold floors send Tennessee homeowner to the crawlspace, but they learn a $300 attic DIY comes first

A Tennessee homeowner looking for the cheapest way to warm up cold floors started by eyeing their crawlspace. 

But after posting their ideas to Reddit's r/Insulation forum, commenters responded with suggestions for a different first move, tackling the attic instead with a roughly $300-$400 do-it-yourself insulation upgrade.

Here's what to know

According to the original poster, the home is a brick house in East Tennessee, and the crawlspace is ventilated but uninsulated, with "some type of vapor barrier underneath." They added that the attic had only a small amount of insulation that they believed was rock wool. OP added, "The floors are cold already and it's just October."

Living on a single income, the homeowner asked whether a lower-cost mix of foam board at the vents, a better vapor barrier, and perhaps a temperature-cutoff vent could help trim heating costs. OP then asked, "Any thoughts on how to proceed on a very tight budget?"

Replies quickly shifted the focus upward.

One commenter wrote, "Start at the top. Air seal and blow in cellulose into [the] attic. Like $300-400 DIY," a cheaper starting point. OP responded to this writing, "That cheap? I was expecting much more… Cellulose is better than fiberglass?"

The commenter then wrote, "Not necessarily. It's what I used though. You'll need to find the link on Home Depot and calculate based on what it says."

Not everyone ignored the space below the house. Another commenter said, "Air sealing the floor from the crawlspace side is super important," and suggested doing the rim joists before insulating under the floor. 

Still, the strongest point of agreement was the sequence. First, seal air leaks before adding insulation. As one commenter put it, "Before you blow in more google air sealing and do that. It's more important than the insulation itself." 

In this case, starting with an attic top-off instead of crawlspace encapsulation-style work could mean a much smaller upfront cost.

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